> fearing that fire will evolve.

Well now I have new nightmares... :)

But in seriousness, I don't know much, but I believe that protein-folding is a hugely complicated problem that still lies at the edge of our understanding, therefore I conclude that we can't really conclude that the options for a replicating, harmful prion are basically harmless.

I mean...we don't even really know how common prions are, right? We only have noticed a handful because they have dramatically bad symptoms. A large number of replicating but harmless prions could exist (right?).

Obviously there's no reason to panic, but considered caution and study seems a better reaction than overconfident dismissal.

I don't know how many conformation changes could plausibly be caused by a prion or how many of them would be stable (and I'd imagine it depends heavily on the protein), but the number of possible conformations is incredibly large for any reasonably large protein.